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Harald Welte laforge at gnumonks.orgOn Thu, Jun 18, 2009 at 11:58:48PM +0200, Harald Welte wrote: > On Thu, Jun 18, 2009 at 11:32:55PM +0200, Harald Welte wrote: > > If we use the knowledge of the behavior as described above, we can also deduct: > > > > * the BS-11 is configured to a NM_ATT_RF_MAXPOWR_R of 0, i.e. it will transmit > > with the power level that is configured by LMT / ipaccess_config. By default > > this is set to 30mW > > > > * the nanoBTS 900 has 20dBm (1800 is 23dBm) TRX output power. bsc_hack is > > configured to a NM_ATT_RF_MAXPOWR_R of 12, i.e. 24dB. This means we are > > transmitting with a mere -4dBm (398uW) or -1dBm (794uW) which would be _really_ > > low. So either the nanoBTS are not following specs, or we're really > > transmitting something that would barely be possible to receive. Or my > > calculations are wrong ;) > > I've now also realised that every CHANNEL ACTIVATE message contains a BS power > and MS power IE with 0x0f as value, i.e. another 30dB decrease in initial power > levels. This really makes me suspicious... at levels that low, everything > should never be working. Probably the MS and BTS cannot operate below a > certain level, and thus they choose whatever is the minimum level they support. For the BTS I'm still puzzled. For the MS, a power level of 0xf (15) means: 13dBm (19mW) output power in GSM900 and 0dBm (1mW) in GSM1800 - which would probably work well unless there's actual uplink interference on the respective channel. -- - Harald Welte <laforge at gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)